# std::rbegin, std::crbegin

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< cpp‎ | iterator

Defined in header `<array>` |  |
Defined in header `<deque>` |  |
Defined in header `<flat_map>` |  |
Defined in header `<flat_set>` |  |
Defined in header `<forward_list>` |  |
Defined in header `<inplace_vector>` |  |
Defined in header `<iterator>` |  |
Defined in header `<list>` |  |
Defined in header `<map>` |  |
Defined in header `<regex>` |  |
Defined in header `<set>` |  |
Defined in header `<span>` |  |
Defined in header `<string>` |  |
Defined in header `<string_view>` |  |
Defined in header `<unordered_map>` |  |
Defined in header `<unordered_set>` |  |
Defined in header `<vector>` |  |
template< class C > auto rbegin( C& c ) -> decltype(c.rbegin()); | (1) | (since C++14) (constexpr since C++17)
template< class C > auto rbegin( const C& c ) -> decltype(c.rbegin()); | (2) | (since C++14) (constexpr since C++17)
template< class T, std::size_t N > std::reverse_iterator<T*> rbegin( T (&array)[N] ); | (3) | (since C++14) (constexpr since C++17)
template< class T > std::reverse_iterator<const T*> rbegin( std::initializer_list<T> il ); | (4) | (since C++14) (constexpr since C++17)
template< class C > auto crbegin( const C& c ) -> decltype(std::rbegin(c)); | (5) | (since C++14) (constexpr since C++17)

Returns an iterator to the reverse-beginning of the given range.

1,2) Returns c.rbegin(), which is typically an iterator to the reverse-beginning of the sequence represented by c.
1) If `C` is a standard Container, returns a `C::reverse_iterator` object.
2) If `C` is a standard Container, returns a `C::const_reverse_iterator` object.
3) Returns a std::reverse_iterator<T*> object to the reverse-beginning of array.
4) Returns a std::reverse_iterator<const T*> object to the reverse-beginning of il.
5) Returns std::rbegin(c), with c always treated as const-qualified.
If `C` is a standard Container, returns a `C::const_reverse_iterator` object.

### Parameters

c | - | a container or view with a `rbegin` member function
array | - | an array of arbitrary type
il | - | an std::initializer_list

### Return value

1,2) c.rbegin()
3) std::reverse_iterator<T*>(array + N)
4) std::reverse_iterator<const T*>(il.end())
5) c.rbegin()

### Exceptions

May throw implementation-defined exceptions.

### Overloads

Custom overloads of `rbegin` may be provided for classes and enumerations that do not expose a suitable `rbegin()` member function, yet can be iterated.

Overloads of `rbegin` found by argument-dependent lookup can be used to customize the behavior of std::ranges::rbegin and std::ranges::crbegin. | (since C++20)

### Notes

The overload for std::initializer_list is necessary because it does not have a member function `rbegin`.

### Example

Run this code

    #include <iostream>
    #include <iterator>
    #include <vector>

    int main()
    {
        std::vector<int> v = {3, 1, 4};
        auto vi = std::rbegin(v); // the type of “vi” is std::vector<int>::reverse_iterator
        std::cout << "*vi = " << *vi << '\n';

        *std::rbegin(v) = 42; // OK: after assignment v[2] == 42
    //  *std::crbegin(v) = 13; // error: the location is read-only

        int a[] = {-5, 10, 15};
        auto ai = std::rbegin(a); // the type of “ai” is std::reverse_iterator<int*>
        std::cout << "*ai = " << *ai << '\n';

        auto il = {3, 1, 4};
        // the type of “it” below is std::reverse_iterator<int const*>:
        for (auto it = std::rbegin(il); it != std::rend(il); ++it)
            std::cout << *it << ' ';
        std::cout << '\n';
    }

Output:

    *vi = 4
    *ai = 15
    4 1 3

### See also

begincbegin (C++11)(C++14) | returns an iterator to the beginning of a container or array (function template)
endcend (C++11)(C++14) | returns an iterator to the end of a container or array (function template)
rendcrend (C++14) | returns a reverse end iterator for a container or array (function template)
ranges::rbegin (C++20) | returns a reverse iterator to a range (customization point object)
ranges::crbegin (C++20) | returns a reverse iterator to a read-only range (customization point object)

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